Poseidon was a major civic god of several cities: in Athens, he was second only to Athena in importance; while in Corinth and many cities of Magna Graecia he was the chief god of the polis. In his benign aspect, Poseidon was seen as creating new islands and offering calm seas. When offended or ignored, he supposedly struck the ground with his trident and caused chaotic springs, earthquakes, drownings and shipwrecks. In the Odyssey Poseidon’s grudge against the protagonist prevented him from coming home to Ithaca. Sailors prayed to Poseidon for a safe voyage, sometimes drowning horses as a sacrifice.

According to Pausanias, Poseidon was one of the caretakers of the oracle at Delphi before Olympian Apollo took it over. Apollo and Poseidon worked closely in many realms: in colonization, for example, Delphic Apollo provided the authorization to go out and settle, while Poseidon watched over the colonists on their way, and provided the lustral water for the foundation-sacrifice. Xenophon‘s Anabasis describes a group of Spartan soldiers in 400-399 BCE singing to Poseidon a paean – a kind of hymn normally sung for Apollo.

Like Dionysus, who inflamed the maenads, Poseidon also caused certain forms of mental disturbance. A Hippocratic text of ca 400 BCE, On the Sacred Disease[1] says that he was blamed for certain types of epilepsy.

The name seems to rather transparently stem from Greekpósis “lord, husband” with a less-transparent -don element, perhaps from dea, “goddess’. If surviving Linear Bclay tablets can be trusted, the name PO-SE-DA-WO-NE (“Poseidon”) occurs with greater frequency than does DI-U-JA (Zeus). A feminine variant, PO-SE-DE-IA, is also found, indicating a lost consort goddess, in effect a precursor of Amphitrite. Tablets from Pylos record sacrificial goods destined for “the Two Queens and Poseidon” and to “the Two Queens and the King”. The most obvious identification for the “Two Queens” is with Demeter and Persephone, or their precursors, goddesses who were not associated with Poseidon in later periods. Poseidon is already identified as “Earth-Shaker”— E-NE-SI-DA-O-NE— in Mycenaean Knossos,[2] a powerful attribute where earthquakes had accompanied the collapse of the Minoan palace-culture. In the heavily sea-dependent Mycenean culture, no connection between Poseidon and the sea has yet surfaced; among the Olympians it was determined by lot that he should rule over the sea (Hesiod, Theogony 456): the god preceded his realm.

Demeter and Poseidon’s names are linked in one Pylos tablet, where they appear as PO-SE-DA-WO-NE and DA-MA-TE, in the context of sacralized lot-casting. In one etymology[citation needed], the ‘DA’ element in each of their names would be connected to a Proto-Indo-European root relating to distribution of land and honors (compare Latin dare “to give”), thus ‘Poseidon’ would mean something like “distribution-lord” or “husband of the distributor”, to match ‘Damater’ “distribution-mother”. Walter Burkert finds that “the second element da- remains hopelessly ambiguous” and finds a “husband of Earth” reading “quite impossible to prove” (Burkert 1985 III.2.3).

Given Poseidon’s connection with horses as well as the sea, and the landlocked situation of the likely Indo-European homeland, some scholars have proposed that Poseidon was originally an aristocratic horse-god who was then assimilated to Near Eastern aquatic deities when the basis of the Greek livelihood shifted from the land to the sea.

In any case, the early all-importance of Poseidon can still be glimpsed in Homer‘s Odyssey, where Poseidon rather than Zeus is the major mover of events.

Poseidon was a son of Cronus and Rhea. In most accounts, he is swallowed by Cronus at birth. However in some versions of the story, he, like his brother Zeus, did not share the fate of his other brother and sisters who were eaten by Cronus. He was saved by his mother Rhea, who concealed him among a flock of lambs pretended to have given birth to a colt, which she gave to Cronus to devour.[3] According to John Tzetzes[4] the kourotrophos, or nurse of Poseidon was Arne, who denied knowing where he was, when Cronus came searching; according to Diodorus Siculus[5] Poseidon was raised by the Telchines on Rhodes, just as Zeus was raised by the Korybantes on Crete.

According to a single reference in the Iliad, when the world was divided by lot in three, Zeus received the sky, Hades the underworld and Poseidon the sea.

Athena became the patron goddess of the city of Athens after a competition with Poseidon. They agreed that each would give the Athenians one gift and the Athenians would choose whichever gift they preferred. Poseidon struck the ground with his trident and a spring sprung up; the water was salty and not very useful, whereas Athena offered them an olive tree. The Athenians (or their king, Cecrops) accepted the olive tree and along with it Athena as their patron, for the olive tree brought wood, oil and food. After the fight, infuriated at his loss, Poseidon sent a monstrous flood to the Attic Plain, to punish the Athenians for not choosing him.

This myth is construed by Robert Graves and others as reflecting a clash between the inhabitants during Mycenaean times and newer immigrants. It is interesting to note that Athens at its height was a significant sea power, at one point defeating the Persian fleet at Salamis Island in a sea battle. Another version of the myth says that Poseidon gave horses to Athens.

Poseidon and Apollo, having offended Zeus, were sent to serve King Laomedon of Troy. He had them build huge walls around the city and promised to reward them well, a promise he then refused to fulfill. In vengeance, before the Trojan War, Poseidon sent a sea monster to attack Troy (it was later killed by Perseus).

Poseidon was the father of many heroes. He is thought to have fathered the famed Theseus.

A mortal woman named Tyro was married to Cretheus (with whom she had one son, Aeson) but loved Enipeus, a rivergod. She pursued Enipeus, who refused her advances. One day, Poseidon, filled with lust for Tyro, disguised himself as Enipeus, and from their union were born the heroes Pelias and Neleus, twin boys. Poseidon also had an affair with Alope, his granddaughter through Cercyon, begetting the Attic hero Hippothoon. Cercyon had his daughter buried alive but Poseidon turned her into the spring, Alope, near Eleusis.

Poseidon fell in love with Pelops, a beautiful youth, son of Tantalus. He took Pelops up to Olympus and made him his lover, even before Zeus did the same with Ganymede. To thank Pelops for his love, Poseidon later gave him a winged chariot, to use in the race against Oenomaus for the hand of Hippodamia.

In the Iliad Poseidon favors the Greeks, and on several occasion takes an active part in the battle against the Trojan forces. However, in Book XX he rescues Aeneas after the Trojan prince is laid low by Achilles.

In the Odyssey, Poseidon is notable for his hatred of Odysseus due to the latter’s having blinded the god’s son Polyphemus. The enmity of Poseidon prevents Odysseus’s return home to Ithaca for many years. Odysseus is even told, notwithstanding his ultimate safe return, that to placate the wrath of Poseidon will require one more voyage on his part.

In the Aeneid, Neptune is still resentful of the wandering Trojans, but is not as vindictive as Juno, and in Book I he rescues the Trojan fleet from the goddess’s attempts to wreck it, although his primary motivation for doing this is his annoyance at Juno’s having intruded into his domain.

A hymn to Poseidon included among the Homeric Hymns is a brief invocation, a seven-line introduction that addresses the god as both “mover of the earth and barren sea, god of the deep who is also lord of Helicon and wide Aegae[9], and specificies his twofold nature as an Olympian: “a tamer of horses and a saviour of ships.”